1. Field of the Invention
This invention concerns apparatus for optically recording on a moving, light sensitive record carrier variable measurement quantities that can be translated into electrical current or voltage variations. In particular, it concerns apparatus comprising a row of light-emitting components which are arranged transversely to the direction of motion of the record carrier and, in addition, an amplitude discrimination arrangement associated with such components for causing the components to emit light onto the record carrier for given amplitude values of the measurement quantities.
2. Description of the Prior Art
In one known apparatus of this kind (German Offenlegungsschrift No. 1,918,771), electroluminescent components are used as the light-emitting components, and a light-sensitive paper or a film, which changes it charge distribution as a function of emitted light, serves as the record carrier. Nothing can be found in the aforementioned Offenlegungsschrift about the design of the amplitude discriminator arrangement and the excitation circuit of the individual light-emitting components.
A device for recording phenomena and, in particular, rapid phenomena that can be translated into electrical current or voltage variations, is known (German Auslegschrift No. 1,448,820) which comprises a row of writing elements arranged in the manner of a comb. The writing elements used are, for instance, semiconductor diodes, specifically, gallium arsenide diodes. The writing elements are driven by a set of mechanically inertialess discriminators which set in operation, individually and automatically, each associated writing element if the recorded current or voltage values fall into a given narrow interval of the measuring range, the individual intervals sequentially covering the range of measurement values to be recorded essentially without gap. It cannot be seen from the aforesaid Auslegeschrift how the discriminators are constructed and in which manner the writing elements are driven by them.
It is also known to employ an oscillograph (U.S. Pat. No. 2,907,622) which comprises several recording elements arranged in a row in the manner of a comb. Each of the recording elements is connected with a series resonant circuit. Additionally such elements are jointly connected on their input sides via amplifiers to the outputs of frequency modulators. An oscillator, which delivers an alternating quantity with a given frequency, is associated with each frequency modulator. The alternating quantity is frequency-modulated by a measurement quantity to be recorded, which quantity has been translated into a voltage variation, so that it is then ensured by the appropriately tuned series resonant circuits preceding the writing elements that a measurement value is always recorded by the writing element whose preceding series resonant circuit is tuned to the frequency characterizing this measurement value.
This above-mentioned oscillograph is disadvantageous in that a relatively large amount of circuitry is required for driving the individual recording elements, i.e, an oscillator and a frequency modulator and a resonant circuit are required for each measurement quantity to be recorded.
It is, therefore, an object of the present invention to provide apparatus for optically recording variable measurement quantities via an amplitude-discriminator arrangement which can be manufactured at comparatively low cost.